The Phantom Monster
by Chocolate Chip Rainbow
Summary: Danny was a fairly normal child living a fairly normal life with his fairly normal parents. All of that changed thanks to an accident that turned him into a monster! Now without parents or a regular life he now runs from the Hero Association as they try to end him. The only thing he has to say to them is "Good luck" Don't own Danny Phantom or One Punch Man. Cover image isn't mine.
1. Chapter 1

**A/N: Hello there, people of the internet! As usual with me I only begin writing fanfiction when I can't get an idea out of my head. Once I get it out I can begin to start focusing on other things in my life. But I figured I might as well get out this idea while it's still fresh yah know?**

 **Now, without further a doo-doo,**

 **Enjoy!**

Danny Fenton was a fairly normal kid who lived a fairly normal life in a fairly normal city. He lived in City Z with his parents who were inventors that were obsessed with the supernatural, namely ghosts. They had chosen this city because it was an ideal spot to conduct experiments due to the city being mostly abandoned. Danny helped out during the experiments he was allowed to.

Even if his parents were weird, he still loved them and wanted to help them as much as possible.

Danny didn't have many friends, which was actually to be expected. He was homeschooled, and the other parents didn't let their kids around him much, because of who his parents were. It was more about them thinking of the safety of their own kid though.

He didn't care either way, he loved his parents, and they loved him.

That's why he loved to help his parents whenever he could, whether it's by cleaning or by helping carry chemicals. He wasn't allowed to when he was younger, but now that he's twelve they let him do it. They even gave him his own hazmat suit for when he wants to work with them.

One day his parents decided to make a portal, one that would connect them to the world that the ghosts live in. The idea sounded farfetched, even for them, but he knew they could do it.

Sadly, the portal failed.

His parents wore downcast expressions as they shut down the lab for the night to get rest. Danny had attempted to cheer them up to no avail. So, with a determined expression, he decided that he would make the portal work for his parents, because he hated seeing them so sad. He didn't go grab his hazmat suit, because his parents had it. He didn't want to alert them of what he was doing, so he decided to go without it.

He went into their lab and turned it on, going straight to the portal. He tried turning it on, but the switch didn't work. Looking at the numerous technological looking things that the portal was made of he was at a loss of what to do. So, he opted to just rearrange most of the pieces to the portal to fix it, it's not like the thing worked before, so he figured this was alright. After a while he was done, and he tried to turn on the switch for the portal.

It didn't work.

He angrily stopped his foot at that; he had tried so hard to fix it. Not being able to think of anything else to do for the moment he glared at the machine. As he glared, something inside of the portal caught his eye. He walked inside of it curiously, to get a better look at the thing. It was another switch. He stared at it for a few moments in puzzlement, and then realized that it must be the way to turn the portal on. His parents must have not tried to flip the switch, because they couldn't see it. He wondered why they put it inside, but then remembered that his parents _do_ tend to make silly mistakes from time to time.

Not dwelling on the thought any longer, he smiled and flipped the switch on. The machine began to turn to life as it made a small whirring sound that gradually got louder. Danny noticed that the air around him changed, it got heavier and took on a green tint. Danny frowned as he began to leave, but tripped and fell before he could get far. He looked down at his foot to see that he had gotten it tangled in some loose wires. He attempted to untangle the wires from his foot, but in his panic he tore them off instead.

That can't be good

The machine's whirring noise began to pick up in speed and volume, and the air turned heavier and greener. It had gotten so bad that even though Danny was free, he struggled to move. He crawled towards the exit of the portal at a slow pace, but it was as fast as he could go. He was almost there, when electricity began to crackle around the machine and it electrocuted Danny. He screamed in pain as the whirring noises of the machine filled his ears. His eyes were squeezed shut as he called for help, for his parents, for anyone. No one came though, as the machine exploded.

When Danny finally crawled out of the machine he felt different, _very_ different. He pulled himself to his feet as he slowly stumbled to one of the mirrors in the lab. He gasped in surprise at what he saw.

His skin was a pale blue and his eyes were a crimson red. His hair was white and he had sharper teeth than he remembered before along with pointed ears. His shirt had been burned off, letting him be able to view his torso. There were small black markings that were on his checks, forearms, and on his upper stomach area. He looked closer at his face and noticed that he had a third eye, but it was currently closed.

He jolted back in surprise when he noticed himself. "A-am I…a m-monster?" He didn't have time to be shocked by his own appearance however, as his parents decided to show up.

"Danny! Are you down here?" His mother called as she entered the room with his father. They caught sight of him, and he felt relief.

"AH! What is that?!" His mother screamed. He felt confused, he was their son, didn't they notice? His parents loved him, of course they would recognize him.

"It's me –" He wasn't able to finish his sentence as his father pulled out a large gun of some sort.

"Danny was down here. Whatever that thing is, it must have gotten to him and destroyed our portal!" His father yelled, before firing off a shot from his gun. A green ball of energy was fired from it and it sped towards Danny. Acting purely on instinct, the boy jumped to the side to evade the blast as it tore scorched the ground where he once stood.

"Wait!" He attempted to stop his parents, but his words were unheard as his mother pulled out a weapon and, alongside his father, tried to kill him. His eyes widened as the shot at him, and he threw out his hands to protect himself. The markings on his forearms shined a bright white as red energy was propelled from his hands. His own shots quickly over powered his parents' as they continued on until one blew a hole in his father's chest, and the other obliterated his mother's entire lower half.

His mother died instantly, while his father wore a look of shock for a moment before he fell to the ground dead as well. Danny looked at his hands in horror of what he had just done. Tears fell from his eyes as he looked at his parent's prone, unmoving bodies. His hands gripped his hair and the markings on his cheeks shined a familiar bright white. He let out a scream, a wail that shook his house and destroyed his surroundings, until the entire place finally collapsed on top of him.

LINE BREAK

The day Danny was first changed was ten years ago. He had learned a while ago that while he may be older now, his body doesn't grow anymore. So he concluded that he would look like a twelve year old forever, not that he cared. He didn't care about much anymore.

While his physical appearance may not have changed much, his attire did. He now wore a short sleeved black t-shirt, with baggy black pants and black shoes. His body became more defined than it was when he was twelve, and he had acquired a lot more abilities in that time as well.

He still resided in City Z, he wanted to be left alone, and this city allowed him to do just that. Though sometimes, the occasional hero or heroes would show up and battle with him, and he would leave for a while after he won. He would always come back sooner or later though.

He was currently lying about in some alleyway when he was confronted by a monster. It had seaweed for hair and Danny could only see one visible eye from where he sat. The monster stopped in front of him and began to speak.

"Hey, I heard that there were a bunch of monsters gathering around here for something _big_." The thing's voice sounded young, but slightly distorted. "Do you know anything about it?" The monster asked.

Danny stared at the monster for a moment with his regular scowl before answering. "No, I don't know about it." He said simply.

"You don't _know_ , or you _do_ know and you just don't wanna tell me." The monster grinned, the seaweed on its head beginning to wiggle around like tentacles.

"I _don't_ know anything about it." Danny reiterated, with an annoyed expression.

"Well, if that's the way you wanna be." The monster grinned wider as its tentacle like seaweed hair darted at Danny. Danny didn't move from his sitting position though, as the seaweed just passed through him. The seaweed monster's grin fell as its face took on a confused expression.

"Hmm?" It questioned while tilting its head to the side. Danny narrowed his eyes at the monster from his spot, before he suddenly disappeared. The monster gasped as Danny was suddenly next to it, with a ball of energy directed at its face.

"Get outta here, before I decide to fry you." Danny threatened with an ominous echo to his voice. The monster took heed to his words as it scurried away after that. Danny sighed as he turned invisible and walked away from the area.

"Who was that?" A black haired teenage girl in gothic clothing asked him as he walked. This was another thing he found out about on that fateful day, he could see ghosts. They were everywhere, and they walked around like people. The one way he could really tell was the faint glow that ghosts had around their bodies, and the fact that they could see him when he was invisible.

"I don't know, Sam." He said with a sigh. He kept his voice low, because even though he was invisible, people could still hear him. "It was just another random monster." Sam was one of the only ghosts that he talked to on a regular basis. He normally just ignored the others, but this one wouldn't leave him alone. She became a sort of 'regular' in his life.

"What did it want?" She asked.

"Something about the gathering of monsters." Danny answered her. They ended up at the abandoned building where Danny usually stays. They saw a blonde haired cyborg in a sleeveless white shirt and jeans walking past the building with a grocery bag. He suddenly stopped, and looked in their direction while simultaneously dropping the bag, making them freeze.

"Ah man, what's Demon Cyborg doing here?" Danny quietly muttered to himself. Sam looked worried as the cyborg man began to walk over towards them. Danny shooed her away, not that she would get hurt by the cyborg, but by _Danny_.

"My sensors are detecting a mass of cooler air in this spot directly. Something such as this isn't normal. This may become a problem in the future. I will swiftly handle it, so that sensei won't have to sully his hands later on. Show yourself!" Genos called as he stood directly in front of Danny.

"Guess I've got no choice huh?" Danny spoke in monotone as he dropped his invisibility. He looked up at the cyborg with an annoyed expression. "What do you want?" He asked him.

Genos looked surprised, but then his eyes hardened. He jumped back away and entered a fighting stance as his arms glowed with power. "You are known as Phantom; I would like to deal with you now, before you become a problem for sensei or the people. Incinerate." Without waiting for Danny to say anything Genos blasted a torrent of fire at Danny. The area Danny stood in was destroyed in an explosion and a dust cloud was formed.

As the dust cloud disappeared, Danny stood in the same spot. His arms were crossed over his body and he had small burns on his body. His shirt couldn't handle the heat and was destroyed along with some of his pants legs.

"Huh, I didn't expect that to be able to hurt me. Looks like my opposite element can also negate my intangibility." Danny muttered as he dropped his arms and glared at the cyborg. "Talking to this guy won't do much; I'll just have to quickly get this over with." Genos then charged towards him and attempted to punch him. Danny let the punch sail through his body and then struck Genos with 3 quick punches to his face and a light kick to his gut that sent him away.

Genos quickly recovered and fired another blast of fire at Danny that was countered by a blast of ice that resulting in a smoke screen of sorts. Danny then appeared in front of Genos with a ball of red energy that he shoved into the cyborg's gut, causing an explosion. When the smoke cleared, Genos was on the ground, looking worse for wear, but still ready to fight.

"Hey! That's Demon Cyborg!"

"He's losing against Phantom!"

"Call for help!"

People had begun to panic as they caught wind of the fight and a few of the civilians called the Hero Association. Danny frowned as he let out a groan. "Damn it…" He cursed. "I guess I'd better start leaving right away…" He muttered to himself. He then dodged a blast of fire from Genos. He fixed Genos with a glare as the cyborg charged at him. The markings on his arms shined as his hands became covered in red energy. He dodged the fire enhanced attacks that the cyborg launched at him for a while before striking out with a fist. His punch blasted Genos's arm off and he quickly followed up with another that took off his leg. Genos fell to the ground as he was unable to properly stand.

"Stay down." Danny ordered as he disappeared before more heroes could arrive. He engaged his invisibility as he took to the skies, away from City Z.

 **A/N: Done! Danny has mostly the same abilities as in the cartoon. The only thing that really changed was his situation and the appearance I gave him.**

 **Tell me what you think! Was it awful? Was it good? What can I do to make it better? If it sucks and you don't tell me I can't really fix it yah know?**

 **That's all I have to say for now.**

 **Buh-bye!**


	2. Chapter 2

**A/N: HI! I hope you're having a good day!**

 **Thanks for the reviews! I'll address them right away!**

 **Of LifeDeathAndAllBetween:** **It's nice to see you again; glad you are enjoying the idea,**

 **Newjack187:** **Yeah, I can't wait either, and I'm the one writing it! Thanks for reading!**

 **Guest:** **Say no more!**

 **InkHaint:** **Don't worry, you got it.**

 **Mince:** **I'm sorry you feel that way. Is there any particular reason for your opinion? Can it be fixed?**

 **TheWhiteTitan:** **I'm glad to be the first!**

 **ThatOnePaperclip:** **Whoa! Don't do that yet! You won't be able to read the next chapters that way will you?**

 **Whelp, that's all of them! Thanks again!**

 **Now, without further a doo-doo,**

 **Enjoy!**

Danny sighed as he felt that he had flown far enough away. He was in City X by the look of things, and it had been a day since he fought Demon Cyborg. When he finally found an abandoned building area, he dropped his invisibility, revealing his still shirtless body and tattered pants.

He had gotten better at controlling his invisibility; even so, holding it for an entire day was a bit tiring. He sat behind one of the pillars of the building as he closed his eyes and decided to rest for a while.

LINE BREAK

"I have eyes on Phantom. I repeat: I have eyes on Phantom. I am in City X requesting back up immediately." Lightning Max watched Phantom through his telescope as the boy slept. He was at a far enough distance to where he deemed it safe as he knew how dangerous Phantom was. He called the Hero Association through his cell phone as soon as he saw him.

"Thank you Lightning Max, you are not to engage Phantom unless faced with no choice. Do not underestimate him based on his size, please wait for back up to arrive." A supervisor on the phone of the Hero Association asked.

"Understood, I'll continue to observe him for now and I'll inform you if he decides to move."

In the Hero Association headquarters there were people on computers with headsets that furiously typed away.

"Are there any available heroes at this time, preferably S rank?" One called into their headset. "Phantom has been spotted in City X with Lightning Max who has requested immediate back up."

"Most of our S class heroes are dealing with the meteor right now. There are few available but they are too far away to reach them at this time." Another talked.

"Let me go handle it. You don't have to send anybody else." A new voice said.

LINE BREAK

Danny awoke with a start as he instantly jumped into a fighting position. 'There's someone here…' He thought to himself as he glanced around. He then prepared to leave the scene.

'I can't let him leave; I have to stall him until back up arrives!' Max determinedly thought to himself as he ran out in front of Danny. "Stop right there! I'll finish you right here!" Max yelled as he caught Danny's attention.

Danny turned to look at Max with a mix of a surprised and confused expression on his face. It then morphed into an annoyed scowl as he glared at the man. "I don't have time to deal with you…" He said before beginning to fly away while activating his intangibility.

Max narrowed is eyes as the front of his shoe opened up and crackled with electricity. "Flying Reverse Roundhouse Lightning Kick!" He yelled as he sent the kick to Danny who was still airborne. Danny had thrown up his arms at the last second as the kick connected with him and resulted in an explosion that sent him to the ground, making a small cloud of dust.

"Oh right I forgot, you're _Lightning_ Max." Danny sighed from the ground as the dust settled. He stood up and turned to look at Max who had landed and assumed a fighting stance.

"Phantom, blunt attacks don't work on you, but it's been shown that energy coated attacks do." Lightning Max stated with confidence.

"The Hero Association seems to be catching on, but don't think you can beat me just because of a lucky shot." Danny frowned as he also assumed a stance. "I'll end this quick…"

Max charged forward at a relatively fast speed, if compared to a regular human's. To Danny the guy was moving slowly. "Lightning Kick!" Max yelled as he launched a foot out at Danny, to which the latter swiftly dodged and countered with a strong gut punch that made him cough up blood and sent him tumbling. Lightning Max stood up once more before engaging Danny in some light close combat, light for Danny that is.

"Lightning Kick Combo!" Max yelled as he sent a barrage of speedy lightning coated kicks towards Danny. Danny dodged all of the attacks with minimal effort, before sending a dozen fast punches to Max's face and chest, before ending it with a roundhouse kick. Danny stalked over to Max's prone form and charged up a ball of red energy as the markings on his arms shined.

"You would've done better if you had stopped yelling out what you're going to do like an idiot. Who'd you think you were dealing with?" Danny aimed the ball at Max's body. "I should get rid of you now though; you could become a problem later on with that lightning of yours…" He suddenly jumped back to dodge a boulder that was thrown at him.

"Let the idiot go." Danny glanced up to see Tatsumaki floating in the air a few yards away.

"Tornado of Terror…are any more of you gonna show up that I have to worry about?" Danny's scowl deepened in irritation. She stared at him with dull eyes.

"No, I made sure I was the only one to come as back up, I won't need help taking you out." She spoke, making Danny's eyes widen in surprise. "I heard tales of how strong you were, and I had to see for myself whether or not they were true. I never expected Phantom to be such a _shorty_ though." She sighed in disappointment, making a vein on Danny's head throb. "Honestly I expected a lot more. How the Hero Association hasn't gotten rid of you yet is astonishing to say the least."

"Like you're one to talk about height!" Danny finally snapped, making her rear back a bit in shock. "You're shorter than me! So if I'm a shorty that would make you a friggin' midget!" He yelled. She glared at him.

"How dare you! I should kill you for that! In fact, I _will_!"

"I'd like to see you try!" He glared back. He'd only known her for a minute and he'd already hated her. She looked down at him as she picked up a few large rocks and fired them at him. He wasn't worried though as the rocks sailed through him harmlessly. She looked a bit surprised at that.

"If I could be killed by pebbles I wouldn't have survived for as long as I have." Danny said with folded arms. "Anything else?" He mocked. She glared as she sent larger rocks his way, but this time she kept them coated in her aura. The first rock managed to hit him but caused no damage. He dodged the rest.

"Fine, if that's all you can do than it's my turn." He fired two blasts of energy towards her. She span at a fast speed, causing a small tornado to appear around her that negated his attacks. She stopped spinning but no longer saw him on the ground in front of her. Before she could search for him she received a dropkick to her back, making her plummet towards the ground. She righted herself in the air before she could touch the ground though, and looked up with a snarl to see Danny floating a distance away from her.

Tatsumaki shot her hands out and attempted to disrupt his Chi. Danny looked at her with a inquisitive expression before frowning and charging at her. Tatsumaki stopped with the Chi disruption and threw up a shield that Danny broke with a single punch. He then kicked her stomach making her curl her body in; he tried to follow up the attack but was knocked away by a powerful pulse of telekinesis.

They both righted themselves in the air and stared at each other. "You're pretty durable, I thought I was hitting you pretty hard there but you just shrugged it off. Congrats, you now have my attention." Danny said dully.

Tatsumaki glared at him. "As if I need your praise, you'll be dealt with soon enough." She spread her arms out as her aura flared out. The gravity in the area greatly increased as her hands began to glow a green light and slightly transparent and sharp green extensions appeared on her hands, like claws.

"If I had a dollar every time I heard that…" Danny trailed off as his own red aura flared. The markings on his forearms shined as his fists glowed a red light. He was unaffected by the increase in gravity as he frowned and readied himself. 'She's stronger than I thought; I'll have to use a bit more power to beat her. I guess that's why she's number 2.' He mused.

Tatsumaki was tired of waiting and charged at him at an impressive speed. She swung one of her telekinetic claws at him and he guarded with his fist, causing a small shockwave. They then engaged in high speed combat, with Danny mostly defending.

'I admit…this is kinda fun.' Danny thought to himself with a tiny smirk. Tatsumaki saw this and snarled in anger.

'He's not taking me seriously at all! I'll teach him his place soon enough.' She then quickly backed away and charged a green light in her hands. It began to swirl and soon turned into a tornado the size of Danny's body that she fired at him. Danny only threw three energy blasts at the tornado and it exploded which resulted in a dust cloud. Danny then ducked as Tatsumaki came flying threw the cloud with a ball of green energy that she tried to ram in his face. She twisted around after she sailed past him and launched the ball of energy at him, along with another accompanying ball of energy.

Danny merely frowned as he smacked the two energy spheres away one after the other. They created small explosions as they sailed away from him. He then glanced back to Tatsumaki and saw her breathing heavily. Her aura was gone and the claws she wielded had disappeared. He sighed as he dropped his aura as well as his glowing fists.

"Yeah, you're done. It was fun while it lasted, thanks." He spoke the words disappointedly and briskly. Tatsumaki glared at him.

"What are you talking about you idiot?" Tatsumaki spoke in labored breaths. "We're still –" She was cut off as Danny appeared behind her.

"Good night." He said simply as he struck the back of her head with his fist, knocking her unconscious. He glanced around from his position in the sky and sighed.

People were all around him, staring at him in awe and fear. They had been recording the fight and taking pictures of him and Tatsumaki while he was distracted. He let out a low growl as his arms glowed once more.

"Get outta here!" He yelled as he began to fire off random shots, destroying some buildings and effectively scaring the daylights out of the civilians. Once they were all running around and panicking enough he flew away.

"I can't keep doing this much more, hopefully I'll have time to rest soon enough…" He muttered to himself through half lidded eyes. He soared through the sky and picked up speed, traveling to the next nearest city.

LINE BREAK

"Once again the elusive Phantom strikes down another hero, S rank 2 Tornado of Terror, bringing truth to his nickname as the 'Hero Hunter'." A newscaster spoke on Saitama's living room TV. He had just saved the town from a falling meteor the other day, sure the townspeople were pissed but at least they were alive.

"Hey Genos, isn't that the guy that you said you fought about 4 days ago?" Saitama asked from his position on the couch.

"Yes sensei that is Phantom, the monster who bested me." Genos paused in his sweeping to answer Saitama's question. He was currently wearing a pink apron.

"Huh? But he looks like a kid." Saitama seemed unsure as he frowned at the images of him fighting Tatsumaki.

"He is extremely powerful sensei, despite his child-like appearance. He bested me with what I believed was minimal effort." Genos spoke, a slight tinge of regret in his tone.

"Huh," Saitama glanced at Genos and then back at the TV with a thoughtful expression on his face. "That seems pretty interesting."

 **A/N: Second chapter DONE!**

 **Tell me what you think! Awful? Good? Somewhere in between? All reviews are welcomed!**

 **That's all I have to say for now!**

 **Buh-bye!**


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